The biosynthesis of cellular polymers of Azotobacter vinelandii N-15 strain using molasses as a carbon source has been optimized. The highest yield of polymer (25.8 % of cell mass) was obtained on a nutrient medium with a molasses concentration of 50 g/l. Using TL-chromatography and IR-spectroscopy the obtained product was identified as polyhydroxybutyrate (PHB), and its properties were investigated. The wetting contact angle was used to characterize the biopolymer film surface properties. According to the results of thermal and thermomechanical studies, it was found that the obtained РHB is characterized by a high thermal stability and heat resistance: the melting point is 462 K; deep destruction and thermooxidative processes begin at the temperatures above 567 K.

Biogenic surfactants (rhamnolipid biocomplex, dirhamnolipid and exopolysaccharide) and polyhydroxyalkanoate biopolymer which are the new biosynthesis products of Pseudomonas sp. PS-17 strain have been obtained. The thermal transformation of these products has been studied in the air in the temperature range of 293-1273 K. Thermolysis and IR spectroscopy revealed a formation of rhamnolipid biocomplex between rhamnolipids and exopolysaccharide upon acidification of the culture fluid supernatant to pH = 3. Cellular polymerpolyhydroxyalkanoate-was identified by UV-Vis spectroscopy. According to the thermal analysis, the melting point and initial degradation temperature of polyhydroxyalkanoate were determined. Using the Vicat method, the heat resistance of the polymer was determined.

Practically important metabolites of Rhodococcus erythropolis Au-1 strain were obtained: trehalose lipids, exopolysaccharide and cellular polymer – polyhydroxyalkanoate. The structures of the products were established by the methods of TLC, IR and UV-Vis spectroscopy. The purification of trehalose lipids from crude extract was carried out using silica gel column chromatography, one of the trehalose lipids fractions was identified as a trehalose dimycolate. The presence of (NН) group was detected in the exopolysaccharide. For the first time, a biodegradable polymer was isolated from bacteria cells of the strain R. erythropolis Au-1, іt was identified as the polyhydroxyalkanoate. The physico-chemical properties of the metabolites of the strain R. erythropolis Au-1 were established: the surface tension of trehalose lipids fractions was 30,5-43,2 mN/m; the emulsification activity of the exopolysaccharide solutions (1-10 g/L) with vaseline oil was 42-58%. The differential thermal analysis was used to define starting temperatures of degradation of trehalose dimycolate (130 °C), exopolysaccharide (180 °C) and polyhydroxyalkanoate (164 °C, melting point 42oC). The obtained results expand the possibilities of practical application of trehalose lipids, exopolysaccharide and polyhydroxyalkanoate of the strain R. erythropolis Au-1.

The temperature and physical-mechanical properties of polyhydroxybutyrate obtained during the cultivation of Azotobacter vinelandii N-14 bacteria strain, polylactic acid, poly(-caprolactone) and their blends were studied. Polymer samples in the form of films with a thickness of 50 m were cast on silicate glass plates applying 3% solutions of biopolymers in chloroform and subjected to heat treatment in an air thermostat at the temperature of 1100C for 20 minutes. It was found that the previous heat treatment of the studied biodegradable polymers increases their heat resistance which is evidenced by the shift of their thermal effects of melting to higher temperature area. It was determined that films based on polyhydroxybutyrate/polylactic acid/poly(-caprolactone) (20:55:25 wt.%) blend possesses improved mechanical properties. The film relative elongation at break increases from 3% to 46% for polyhydroxybutyrate and for the mixture, respectively. This is explained by the presence of poly(-caprolactone) polymers in above mixture. At the same time, despite the lower tensile strength characteristic which are typical of poly(-caprolactone), this value is higher for the polymer blends than for polyhydroxybutyrate (38.3 and 33.0 MPa, respectively). This is due to the high polylactic acid content (55%) in the polymer composition. The presence of poly(-caprolactone) (25%) in the blend improves the fluidity of its melt which will enable to reduce the temperature of product formation. The derived polymer mixture is recommended for the manufacturing of various packaging materials for food, agricultural and pharmaceutical products.

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